<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>欢迎注册</title>
    <link href="css/register.css" rel="stylesheet">
</head>
<body>

<div class="form-div">
    <div class="reg-content">
        <h1>欢迎注册</h1>
        <span>已有帐号？</span> <a href="login.html">登录</a>
    </div>
    <form id="reg-form" action="/Login_Web_exploded/registerServlet" method="post">

        <table>

            <tr>
                <td>用户名</td>
                <td class="inputs">
                    <input name="username" type="text" id="username" >
                    <br>
                    <span id="username_err" class="err_msg">${username_err}</span>
                </td>

            </tr>

            <tr>
                <td>密码</td>
                <td class="inputs">
                    <input name="password" type="password" id="password">
                    <br>
                    <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                </td>
            </tr>

            <tr>
                <td>验证码</td>
                <td class="inputs">
                    <input name="checkCode" type="text" id="checkCode">
                    <br>
                    <span id="checkCode_err" class="err_msg">${checkCode_err}</span>
<%--                    <img src="imgs/a.jpg">--%>
                    <img id="checkCodeImg" src="checkCodeServlet">
                    <a href="#" id="changeImg">看不清？</a>
                </td>
            </tr>

        </table>

        <div class="buttons">
            <input value="注 册" type="submit" id="reg_btn">
        </div>
        <br class="clear">
    </form>

</div>
<script >

    //1. 给用户名输入框绑定 失去焦点事件
    document.getElementById("username").onblur = function () {
        // alert("hh")
        //2. 发送ajax请求
         //获取用户名的值
        var username = document.getElementById("username").value;
        // alert(username)
       //2.1. 创建核心对象
         var xhttp;
         if (window.XMLHttpRequest) {
             xhttp = new XMLHttpRequest();
        } else {
            // code for IE6, IE5
            xhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        alert(xhttp);
        //2.2. 发送请求
        xhttp.open("GET", "http://localhost:8080/Login_Web_exploded/selectUserServlet?username="+username);
        xhttp.send();
       // 2.3. 获取响应
        xhttp.onreadystatechange = function() {
            if (this.readyState == 4 && this.status == 200) {
                //alert(this.responseText);
                //判断
                if(this.responseText == "true"){
                    //用户名存在，显示提示信息
                    document.getElementById("username_err").style.display = '';
                }else {
                    //用户名不存在 ，清楚提示信息
                    document.getElementById("username_err").style.display = 'none';
                }
            }
        };

    }

    document.getElementById("changeImg").onclick = function () {
        //路径后面添加时间戳的目的是避免浏览器进行缓存静态资源
        document.getElementById("checkCodeImg").src = "/Login_Web_exploded/checkCodeServlet?"+new Date().getMilliseconds();
    }
</script>
</body>
</html>